Update article.md

change "imprefect" to "imperfect"

Author: Burkehaven

1-js/02-first-steps/03-strict-mode/article.md

@@ -2,7 +2,7 @@
 
 For a long time JavaScript was evolving without compatibility issues. New features were added to the language, but the old functionality did not change.
 
-That had the benefit of never breaking the existing code. But the back side is that any mistake or an imprefect decision made by JavaScript creators got stuck in the language forever.
+That had the benefit of never breaking the existing code. But the back side is that any mistake or an imperfect decision made by JavaScript creators got stuck in the language forever.
 
 It had been so before 2009 when ECMAScript 5 (ES5) appeared. It added new features to the language and modified some of the existing ones. To keep the old code working, most modifications are off by default. One needs to enable them explicitly with a special directive `"use strict"`.